Wavelength Conversion Element Using Zinc Oxide Matrix
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Solution Overview
Problem
Conventional wavelength conversion elements for LEDs suffer from light scattering due to refractive index differences between phosphor particles and organic silicone resin matrices, leading to reduced optical output and vulnerability to heat and ultraviolet radiation.
Innovation Solution
A wavelength conversion element using zinc oxide as a matrix in a c-axis orientation or single crystalline zinc oxide is employed, which reduces light scattering and enhances resistance to heat and ultraviolet radiation, allowing for higher optical output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphor particles are dispersed in silicone resin to form a phosphor layer, then the phosphor layer can be formed and cured, but the silicone resin is deteriorated by heat and ultraviolet radiation from high-brightness LED chips
Solution Approach 1:
The patent changes the fundamental parameter of the matrix material from organic silicone resin to inorganic substances (glass, zinc oxide, magnesium oxide). This material substitution fundamentally alters the resistance properties to heat and UV radiation, transforming the phosphor layer from UV-sensitive to UV-resistant while maintaining formability through controlled particle dispersion and sintering processes
Solution Approach 2:
The patent creates composite structures by dispersing phosphor particles within inorganic matrix materials (glass or metal oxides). This composite approach combines the optical properties of phosphor particles with the thermal and UV stability of inorganic matrices, achieving both light conversion functionality and resistance to heat/UV deterioration simultaneously
2Illumination intensity
If phosphor particles with high refractive index (1.7 or more) are embedded in silicone resin with refractive index of 1.4, then the phosphor layer can be formed, but a considerable ratio of light is scattered at the interface between phosphor and resin
Solution Approach 1:
The patent changes the refractive index parameter of the matrix material by substituting silicone resin (n=1.4) with inorganic materials having higher refractive indices closer to phosphor particles. Glass matrices achieve n=1.5-1.7, and metal oxide matrices achieve n=1.8-2.0, thereby reducing the refractive index difference from 0.4 to 0.1-0.3 and minimizing light scattering at interfaces
Solution Approach 2:
The patent converts the potentially harmful effect of refractive index mismatch into a beneficial outcome by selecting inorganic matrix materials whose refractive indices naturally align better with phosphor particles. The higher refractive index of inorganic matrices not only reduces scattering but also enhances light extraction efficiency from the LED structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of zinc oxide as a matrix in the wavelength conversion element significantly improves the optical output and durability of LED elements and semiconductor laser light emitting devices by minimizing light scattering and maintaining performance under heat and UV exposure.
Implementation Method 1
due to the refractive index difference (0.4) between the refractive index of the phosphor (1.8) and the refractive index of the silicone resin (1.4), a considerable ratio of light is scattered at an interface between the phosphor and the resin
Implementation Method 2
a matrix using not an organic substance such as a silicone resin which is liable to be deteriorated by heat and ultraviolet radiation but an inorganic substance which is less liable to be deteriorated by heat and ultraviolet radiation
Implementation Method 3
an inorganic substance which is less liable to be deteriorated by heat and ultraviolet radiation
Data Source
AI summary
A wavelength conversion element disclosed in the present application includes a phosphor layer including a plurality of phosphor particles and a matrix that is located among the plurality of phosphor particles and is formed of zinc oxide. The zinc oxide is columnar crystals or a single crystal in a c-axis orientation.